基于植物修复铀矿冶尾矿库退役后流出的铀离子污染的实验研究

发布时间：2018-09-18 21:50

【摘要】：近年来,越来越多的铀矿冶尾矿库即将退役或已经退役,退役后的铀矿冶尾矿库流出的铀离子对环境产生严重的影响,对退役后的铀矿冶尾矿库铀离子污染的治理已经刻不容缓。目前治理铀矿冶尾矿库污染土壤的方法主要分为物理法、化学法和植物修复法。相对于物理法和化学法,植物修复法具有成本低,对土壤扰动小,二次污染小等特点点。然而铀矿冶尾矿库的复杂性及植物修复技术的局限性决定了应用植物修复退役后的铀矿冶尾矿库污染需要结合铀矿冶尾矿库的实际情况。本研究通过调查退役后的铀矿冶尾矿库污染的实际状况,查阅文献,筛选铀富集植物,实验研究植物修复铀矿冶尾矿库的相关问题,最终为应用植物修复退役后的铀矿冶尾矿库铀离子污染提供科学依据。具体工作如下:(1)对我国退役后的铀尾矿库流出的铀离子迁移研究表明,铀离子最终会在土壤内积累,我国铀矿冶尾矿库铀离子污染问题其根本就是铀矿冶尾矿库铀离子污染土壤问题。实地调查铀矿冶尾矿库退役后土壤的理化性质,对铀离子在退役后的铀矿冶尾矿库的存在形态、分布状况做深入了解。调查发现,我国铀矿冶尾矿库污染情况严重,污染土壤因尾矿库渗水等原因,土壤p H值在5~7之间,土壤偏酸性,铀主要以铀酰离子或羟基络合物存在,污染深度在30cm左右,利用植物修复铀矿冶尾矿库流出的铀离子污染土壤具有可行性。同时铀尾矿库污染土壤内含有大量重金属离子,铀尾矿库污染土壤是严重的放射性-重金属复合污染,利用植物修复铀矿冶尾矿库流出的铀离子污染土壤需要考虑植物对重金属离子的耐性。(2)调查铀尾矿库植物资源,筛选可用于修复铀矿冶尾矿库铀离子污染的植物。铀矿冶尾矿库污染区植物资源丰富,其中草本植物约占80%,木本植物约占20%,但铀尾矿库区植物搭配不合理,铀尾矿库生态环境恶化,造成铀离子污染进一步扩大。铀尾矿库植物中,牛筋草、水莎草、辣蓼、狗尾草、鬼针草、马唐既是优势植物也是铀富集能力较强强的植物,可用于铀尾矿库铀污染的植物修复。(3)本文以菠菜、小白菜、空心菜为研究对象,研究铀浓度对植物发芽及生长的影响。在铀浓度分别为0.0、20.0、50.0、100.0、250.0 mg.kg-1溶液内,发现铀浓度对植物发芽率影响较小。但随着铀浓度的升高,植物生长状况不同,其中小白菜在两周内随铀浓度升高死亡率升高明显,空心菜死亡率较低,均低于10%。在0.0、50.0、75.0、100.0、250.0 mg.kg-1铀浓度的土壤内,菠菜、小白菜、空心菜富集铀的能力,实验结果表明,菠菜较小白菜、空心菜富集铀的能力强,在100.0 mg.kg-1铀浓度土壤内,菠菜地上部分铀含量187 mg.kg-1,地下部分铀含量高达313 mg.kg-1,而小白菜在铀浓度为250.0 mg.kg-1条件土壤下mg全部死亡。在铀浓度为100.0 mg.kg-1、铜浓度为100.0 mg.kg-1土壤内,植物单一种植和植物混合种植植物铀富集效果,实验结果表明,三种植物在铜离子作用下,铀富集能力下降,而采用两种不同植物混合种植富集铀效果更好,因此利用铀富集植物混合种植修复铀尾矿库污染土相比于单一植物种植修复效果要好。施肥尽管会增加植物生物量,但有可能造成植物富集铀能力下降
[Abstract]:In recent years, more and more uranium tailings ponds are about to be decommissioned or decommissioned. Uranium ions from decommissioned uranium tailings ponds have a serious impact on the environment. It is urgent to control uranium ion pollution in decommissioned uranium tailings ponds. Chemical and phytoremediation methods. Compared with physical and chemical methods, phytoremediation methods have the characteristics of low cost, less disturbance to soil and less secondary pollution. However, the complexity of uranium mine tailings reservoir and the limitations of phytoremediation technology determine that the application of Phytoremediation in decommissioned uranium mine tailings reservoir needs to be combined with uranium mine tailings reservoir. In this study, through investigating the actual situation of uranium mine tailings pond pollution after decommissioning, consulting literature, screening uranium enrichment plants, experimental study of phytoremediation of uranium mine tailings pond related issues, ultimately for the application of phytoremediation of decommissioned uranium mine tailings pond uranium ion pollution provides a scientific basis. The study of uranium ion migration from decommissioned uranium tailings reservoirs in China shows that uranium ions will eventually accumulate in the soil. The problem of uranium ion pollution in uranium tailings reservoirs in China is fundamentally the problem of uranium ion contaminated soil in uranium tailings reservoirs. The investigation shows that the contamination of uranium tailings ponds in China is serious, the contaminated soil is caused by the seepage of the tailings ponds, the soil P H value is between 5 and 7, and the soil is acidic. Uranium mainly exists in uranyl ion or hydroxyl complex, and the contamination depth is about 30 cm. Uranium ion from uranium tailings pond is feasible to pollute the soil. At the same time, there are a lot of heavy metal ions in the soil polluted by uranium tailings pond. The soil polluted by uranium tailings pond is a serious radioactive-heavy metal compound pollution. (2) Investigation of plant resources in uranium tailings reservoir and screening of plants for remediation of uranium ion pollution in uranium tailings reservoir. There are abundant plant resources in the polluted area of uranium tailings reservoir, of which herbaceous plants account for about 80% and woody plants account for about 20%. However, unreasonable plant mix in the uranium tailings reservoir area leads to the deterioration of the ecological environment of uranium tailings reservoir and further expansion of uranium ion pollution. Among the plants in uranium tailings pond, Sargassum japonica, Cyperus aquatica, Polygonum polygonum, Sargassum setaria, Potentilla nipponica are both dominant plants and plants with strong uranium enrichment ability, which can be used for the phytoremediation of uranium contaminated uranium in uranium tailings pond. (3) In this paper, spinach, cabbage and spinach were studied to study the effect of uranium concentration on plant germination and growth. In 0.0, 20.0, 50.0, 100.0, 250.0 mg.kg-1 solution, it was found that uranium concentration had little effect on plant germination rate, but with the increase of uranium concentration, plant growth was different. The mortality of Chinese cabbage increased significantly with the increase of uranium concentration in two weeks, and that of Chinese cabbage was lower than 10%. In 0.0, 50.0, 75.0, 100.0, 250.0 mg.kg-1 uranium concentration, the mortality of Chinese cabbage was lower than 10%. The results showed that spinach was smaller than Chinese cabbage, and Chinese cabbage had stronger ability to enrich uranium. In 100.0 mg.kg-1 uranium concentration soil, the uranium content of spinach was 187 mg.kg-1 in the aerial part, 313 mg.kg-1 in the underground part and 250.0 mg.kg-1 in the soil of Chinese cabbage. Uranium enrichment effect of single plant and mixed plant in soil with 100.0 mg.kg-1 uranium concentration and 100.0 mg.kg-1 copper concentration was studied. The results showed that uranium enrichment ability of three plants decreased under the action of copper ions, but it was better to enrich uranium by mixing two different plants. Bio-mixed planting is more effective than single plant planting in remediation of contaminated soil in uranium tailings reservoir. Fertilization may increase plant biomass, but it may decrease the ability of plant to enrich uranium.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X753;X173

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